Adjustable-barrel curling iron

ABSTRACT

A radially adjustable barrel, a barrel-adjustment assembly, a radially adjustable heater assembly, and a radially adjustable distal-tip assembly. The barrel is radially adjustable between expanded and contracted positions having different diameters. The barrel-adjustment assembly includes a rotary ring defining a spiral cam guide and includes a cam follower attached to the barrel. The heater assembly includes a post, at least one heater, and at least one spring mounting the heater to the post and biasing the heater radially outward. In use, rotating the ring rotates the spiral cam guide, which displaces the cam follower radially inward or outward, which in turn displaces the outer end of the barrel radially inward or outward to decrease or increase the diameter of the barrel. As the diameter of the barrel is adjusted, the heaters remain in contact with the barrel due to the outwardly biasing influence of the spring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No. 12/880,427, filed Sep. 13, 2010, which application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/241,526, filed Sep. 11, 2009, both of which are hereby incorporated herein by reference.

BACKGROUND

Many women use electric hair-care appliances such as hair dryers, flat irons, and curling irons to style their hair. Conventional curling irons have a heated barrel that is used to create curls in the hair. Different-sized curls are sometimes desirable to create different styles suited for an occasion, outfit, trend, preference, current hair-length, etc. To create different-sized curls, different-sized curling iron barrels must be used. Thus, in order to be able to style their hair with different-sized curls, many women have several different curling irons each with a different-sized barrel. However, many women have limited storage space for curling irons and other hair-care appliances, and arranging for sufficient storage space can be a real problem.

In addition, there are usually a limited number of electrical outlets available in bathrooms, where most hairstyling is done. For women who use multiple electric hair-care appliances, it's common to add plug-in outlet expansions and/or power strips. This can lead to a potential safety hazard by too much current draw interfering with GFCI operation and/or causing circuit overloads.

Accordingly, it can be seen that there exists a need for a better way for women to conveniently and safely create different-sized curls in their hair. It is to the provision of solutions to this and other problems that the present invention is primarily directed.

SUMMARY

The present invention relates to adjustable-barrel curling irons for curling hair into different-sized curls. In an example embodiment there is provided a curling iron including a handle, a pivotal clip, a radially adjustable barrel, a barrel-adjustment assembly, a radially adjustable heater assembly, and a radially adjustable distal-tip assembly. The barrel is radially adjustable between expanded and contracted positions having different diameters. The barrel-adjustment assembly includes a rotary ring defining a spiral cam guide and includes a cam follower attached to the barrel. The heater assembly includes a post, at least one heater, and at least one spring mounting the heater to the post and biasing the heater radially outward. In use, rotating the ring rotates the spiral cam guide, which displaces the cam follower radially inward or outward, which in turn displaces the outer end of the barrel radially inward or outward to decrease or increase the diameter of the barrel. As the diameter of the barrel is adjusted, the heaters remain in contact with the barrel due to the outwardly biasing influence of the spring.

These and other aspects, features, and advantages of the invention will be understood with reference to the drawing figures and detailed description herein, and will be realized by means of the various elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following brief description of the drawings and detailed description of the invention are explanatory of example embodiments of the invention, and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an adjustable-barrel curling iron according to a first example embodiment of the present invention, showing an adjustable barrel in a fully expanded position.

FIG. 2 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 1, with the barrel and distal tip not shown to reveal its internal parts.

FIG. 3 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 1, with the barrel and a portion of the handle not shown to reveal its internal parts.

FIG. 4 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 1, with the barrel and a portion of the handle not shown to reveal its internal parts.

FIG. 5 is a perspective view of the adjustable-barrel curling iron of FIG. 1, with the barrel, heater assembly, and a portion of the handle not shown to reveal its internal parts.

FIG. 6 is a perspective view of the adjustable-barrel curling iron of FIG. 1, with the barrel and a portion of the heater assembly not shown to reveal its internal parts.

FIG. 7 is a perspective view of a portion of the barrel of the adjustable-barrel curling iron of FIG. 1, showing its cylindrical shape and spiral configuration.

FIG. 8 is a perspective view of a portion of the barrel of the adjustable-barrel curling iron of FIG. 1, showing the elongate clip mounted to it.

FIG. 9 is an opposite perspective view of the portion of the barrel of the adjustable-barrel curling iron of FIG. 8.

FIG. 10 is a perspective view of the adjustable-barrel curling iron of FIG. 1 with the barrel-adjustable assembly adjusted to a fully contracted, smallest-diameter position.

FIG. 11 shows the adjustable-barrel curling iron of FIG. 10 with the barrel-adjustable assembly adjusted to a partially contracted, intermediate position.

FIG. 12 shows the adjustable-barrel curling iron of FIG. 10 with the barrel-adjustable assembly adjusted to the fully expanded, largest-diameter position.

FIG. 13 is a plan view of a portion of the adjustable-barrel curling iron of FIG. 10.

FIG. 14 is a cross-sectional view of the adjustable-barrel curling iron of FIG. 13.

FIG. 15 is a plan view of a portion of the adjustable-barrel curling iron of FIG. 12.

FIG. 16 is a cross-sectional view of the adjustable-barrel curling iron of FIG. 15.

FIG. 17 is an exploded perspective view of the adjustable-barrel curling iron of FIG. 1.

FIG. 18 is a perspective view of a portion of an adjustable-barrel curling iron according to a second example embodiment of the present invention, showing an adjustable barrel in a fully expanded position.

FIG. 19 is an exploded perspective view of the adjustable-barrel curling iron of FIG. 18.

FIG. 20 is a perspective view of a portion of an adjustable-barrel curling iron according to a third example embodiment of the present invention, showing an adjustable barrel in a fully expanded position.

FIG. 21 is a perspective view of the barrel of the adjustable-barrel curling iron of FIG. 20.

FIG. 22 is a perspective view of a portion of an adjustable-barrel curling iron according to a third example embodiment of the present invention, with the barrel and distal tip not shown to reveal its internal parts.

FIG. 23 is a perspective view of the barrel of the adjustable-barrel curling iron of FIG. 22.

FIG. 24 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 22, showing the barrel in an intermediate position.

FIG. 25 shows the adjustable-barrel curling iron of FIG. 24 adjusted to a fully contracted, smallest-diameter position.

FIG. 26 is a perspective cross-sectional view of a portion of the adjustable-barrel curling iron of FIG. 22, showing details of the distal tip.

FIG. 27 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 22, showing the distal tip removed.

FIG. 28 is another perspective view of the portion of the adjustable-barrel curling iron of FIG. 27.

FIG. 29 is a perspective view of a portion of the heater assembly of the adjustable-barrel curling iron of FIG. 22.

FIG. 30 is a perspective view of a portion of the adjustable-barrel curling iron of FIG. 22, with a portion of the handle not shown to reveal its internal parts.

FIG. 31 is another perspective view of the portion of the adjustable-barrel curling iron of FIG. 30.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention may be understood more readily by reference to the following detailed description of the invention taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this invention is not limited to the specific devices, methods, conditions, or parameters of the example embodiments described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only. Thus, the terminology is intended to be broadly construed and is not intended to be unnecessarily limiting of the claimed invention. For example, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, the term “or” means “and/or,” and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. In addition, any methods described herein are not intended to be limited to the sequence of steps described but can be carried out in other sequences, unless expressly stated otherwise herein. Any and all patents and other publications identified in this specification are incorporated by reference as though fully set forth herein.

With reference now to the drawing figures, wherein like reference numbers represent corresponding parts throughout the several views, FIGS. 1-17 show an adjustable-barrel curling iron 10 according to a first example embodiment. Referring particularly to FIGS. 1-2, the curling iron 10 includes a handle 12, a pivotal clip 14, a radially adjustable barrel 16, a barrel-adjustment assembly 18, a radially-adjustable heater assembly 20, and a distal tip assembly 22.

The handle 12 can be of a conventional type used in commercially available curling irons, with a generally cylindrical and elongated shape, as depicted. A user interface 24 includes controls (not shown), for example, as parts of the handle 12. The user interface 24, including internal controls, can be of a conventional type used in commercially available curling irons, for example, a temperature control circuit for controlling the temperature, an on/off switch, and other operational controls of the curling iron 10.

The pivotal clip 14 can be of a conventional typical used in commercially available curling irons. Thus, the pivotal clip 14 is pivotally coupled to a fixed component of the curling iron 10 so it can pivot between an open position (not shown) and a closed position (see FIG. 1) where it clamps hair down onto the barrel 16 for curling. For example, the pivotal clip 14 can be mounted to the handle 12 adjacent its distal end and include an actuator lever 26 that is depressed by the user to pivot the hair-engaged clamp 28 away from the barrel 16.

Referring particularly to FIGS. 2-6, the barrel-adjustment assembly 18 is located at the distal end portion of the handle 12 and the proximal end portion of the barrel 16. The barrel-adjustment assembly 18 includes a rotary drive assembly having a spiral cam guide and it includes a cam follower that is attached to the barrel 16. When the rotary drive assembly is operated, its spiral cam guide drives the cam follower to radially adjust the barrel 16.

In the depicted embodiment, for example, the rotary drive assembly includes a fixed ring 30 and rotary collar 32. The fixed ring 30 is attached to the handle 12 and does not move. The rotary collar 32 surrounds a transverse rotary ring 34 that defines the spiral cam guide 36. The rotary collar 33 provides a ready location for user to grasp to rotate the ring 34 relative to the handle 16. In typical commercial embodiments, the spiral cam guide 36 is formed by a spiral groove formed in the rotary ring 34, for example, about 3 mm deep. These components can be made of a material such as a hard plastic.

In addition, in the depicted embodiment the cam follower 41 is formed by the proximal end of an elongate clip 40. The cam follower 41 extends into the spiral cam groove 36 of the rotary collar ring 34. Thus, when the rotary collar 32 is rotated by a user, the cam follower 41 is guided radially inward or outward by the spiral cam groove 36. In other embodiments the cam follower is a separate piece that is attached to the clip or the clip itself is formed as an integral feature of the barrel. Additional details of the cam follower 41 and its relationship to the barrel 16 will be described below.

Turning now to the radially adjustable heater assembly 20, it includes at least one heater 21 and a central rotary post 38. The rotary post 38 extends freely through and is not driven or constrained by the fixed ring 30, and is coupled to and driven by the rotary collar 32. For example, the fixed ring 30 can have a central circular opening 31 (see FIG. 17) through which the rotary post 38 freely extends. And the rotary collar ring 34 can have a central opening 33 through which the rotary post 38 extends, with the collar opening and the post having a conforming non-circular geometry. Electric power wires or leads 42 for the heaters 21 can also extend through the fixed ring opening 31 and wire openings 35 in the collar ring 34 (see FIGS. 6 and 17). Also, the proximal end of the post 38 can include a stopper 44 and the handle 12 can include at least one cradle portion 46 that receives the post and abuts the stopper to constrain the post from linear movement, while still permitting its free-floating rotational movement.

The heaters 21 can be provided by conventional electric resistance heating elements 53 in housings 55, as depicted. There are three of the heaters 21 shown in the depicted embodiment. Because there are three heaters 21, the rotary post 38 in this embodiment is has a portion that is three-sided, that is it has a triangular transverse cross-section. According, the central opening 33 of the rotary collar ring 34 has a conforming triangular shape and is sized so that the post 38 fits through it only when properly oriented. Thus, rotation of the rotary collar 32 drives the rotary post 38 to rotate with the collar. In other embodiments, there are more or fewer of the heaters 21. So for embodiments with eight heaters 21, the rotary post and the collar ring central opening 33 are octagonal. And in still other embodiments, the post has another regular or irregular shape, regardless of the number and shape of heaters used or is circular and is attached to the rotary ring by fasteners.

The heaters 21 are biased radially outward relative to the rotary post 38. For example, each of the heaters 21 can be mounted to the rotary post 38 by at least one spring. In the depicted embodiment, the springs are provided by leaf springs 48 (see also FIG. 9) that include heater clips 51 that hold the heaters on the leaf springs. This enables the heaters 21 to remain in constant and continuous contact with the barrel 16 to provide even and uniform heating. In other embodiments, other springs such as torsion or coil springs are used. In any event, the heaters are biased radially outward toward their least radially compact position, and are squeezed down radially inward toward their most radially compact position when the barrel is adjusted to a smaller diameter, as described in more detail below. In other embodiments in which the cam follower is also attached to one of the heaters, the heaters are biased radially inward toward their most radially compact position, and are pulled radially outward toward their least radially compact position when the barrel is adjusted to a larger diameter, as described in more detail below. To insure proper heating of the barrel 16, a thermistor can be attached to the barrel to provide feedback to the temperature control circuit.

Referring now to FIGS. 7-9, the barrel 16 and the elongate clip 40 are constructed from a strong, flexible, thermal-conductive material, such as light-gauge steel. The material is initially in the shape of a flat sheet, and is then rolled into a generally cylindrical shape, with an inner end 52, an outer end 54, and an overlapping middle portion 56 in a spiral configuration. When the barrel 16 is adjusted to a relatively larger diameter, the middle overlapping portion 56 is reduced, and similarly when the barrel is adjusted to a relatively smaller diameter, the middle overlapping portion is enlarged. The barrel 16 can be provided with its neutral state being the smallest diameter desired, the largest diameter desired, or an intermediate diameter (between the smallest and largest diameters desired) for a given size of curling iron 10. In the first design, moving the outer end 54 radially outward will cause the barrel 16 to increase in diameter, and when the outer end is released the barrel will return to more-or-less its original position with the smallest diameter. Similarly, in the second design, moving the outer end 54 radially inward will cause the barrel 16 to decrease in diameter, and when the outer end is released the barrel will return to more-or-less its original position with the largest diameter. In the depicted embodiment, the barrel 16 is provided with its neutral state being an intermediate diameter, so moving the outer end 54 radially outward or inward will cause the barrel to increase or decrease in diameter, respectively, and then releasing the outer end will allow the barrel to return to more-or-less its original position with the intermediate diameter. The inner end 52 of the barrel 16 is not fixed in place, so as the outer end 54 is adjusted radially inward or outward, the resiliency of the barrel material causes the inner end to expand radially outward as much as permitted to maintain the cylindrical shape at all positions. And the outwardly-biased heaters 21 will always push radially outward on the barrel 16 to that it will always be in the largest-diameter position permitted by the barrel-adjustment assembly 18.

The elongate clip 40 is coupled to the barrel 16 adjacent its outer end 54. The elongate clip 40 can be so coupled by for example spot welding, a longitudinal “C” joint snapped onto the edge of the outer end 54 with a friction fit, by adhesives, or by other conventional bonding and/or attachment techniques. In embodiments in which the elongate clip 40 has a curved or angled profile, the barrel 16 can include one or more fold lines 58 so the outer end 54 of the barrel 16 lies close to the rest of the barrel and does not protrude away from it.

The cam follower 41 is formed at the proximal end of the elongate clip 40 and extends proximally and longitudinally from the barrel 16. The spiral cam guide 36 is slightly oversized so that the cam follower 41 can easily slide and be guided along its spiral length. The shape of the spiral cam guide 36 is preferably selected so that the barrel 16 is concentric at every position as the cam follower 41 is guided radially inward and outward by the spiral cam guide 36.

The cam follower 41 can include an enlarged head portion 60 that fits through an enlarged groove portion 62 of the spiral groove 36 (see FIG. 12) but does not fit through the rest of the groove. In this way, the enlarged head portion 60 can be inserted through the enlarged groove portion 62 until it extends out the other side, and then rotated out of that groove portion so that the cam follower 41 is locked into the spiral groove and cannot be pulled out of it. In the depicted embodiment, for example, the enlarged groove portion 62 is formed by two flaps formed by the cam follower and folded over to provide an increased thickness. In addition, the elongate clip 40 can include one or more hooks 64 that extend longitudinally and distally from its distal end, with the hooks loosely receiving therethrough in a sliding fashion the middle overlapping portion 56 of the barrel 16 so that the barrel changes its diameter generally uniformly along its entire length.

Having described the major components and construction of the curling iron 10, its operation and use will now be described with reference to FIGS. 10-16. In FIGS. 10, 13, and 14, the barrel 16 is the fully contracted, smallest-diameter position, with the cam follower 41 of the elongate clip 40 at the radially innermost end 66 of the spiral cam guide 36. The heaters 21 are in their fully contracted, most radially compact position, contacting and biasing radially outward against the barrel 16 due to the biasing influence of the springs 48 for good heat transfer to the barrel. The curling iron 10 in this position can be used to make smaller-diameter curls.

As the rotary collar 32 is rotated (as indicated by the angular directional arrow of FIG. 11), the spiral cam guide 36 is rotated with it, thereby pulling the cam follower 41 of the elongate clip 40 radially outward (as indicated by the linear directional arrow of FIG. 11). Because the elongate clip 40 is attached to the outer end 54 of the barrel 16, this causes the barrel to unwind to the intermediate-diameter position of FIG. 11. The heaters 21 are expanded to their radially intermediate position, contacting and biasing radially outward against the barrel 16 due to the biasing influence of the spring 48 for good heat transfer to the barrel. The curling iron 10 in this position can be used to make intermediate-diameter curls.

As the rotary collar 32 is rotated further, the barrel 16 is unwound further. In FIGS. 12, 15, and 16, the barrel 16 is has been adjusted to the fully expanded, largest-diameter position, with the cam follower 41 of the elongate clip 40 at the radially outermost end 68 of the spiral cam guide 36 (excluding the enlarged portion 64 for assembly/disassembly of the cam follower into the spiral cam guide). The heaters 21 are in their fully expanded, least radially compact position, contacting and biasing radially outward against the barrel 16 due to the biasing influence of the spring 48 for good heat transfer to the barrel. The curling iron 10 in this position can be used to make larger-diameter curls.

To adjust the barrel 16 back to the smaller-diameter position, the rotary collar 32 is rotated in the opposite direction. The opposite-direction rotation of the spiral cam guide 36 of the rotary collar 32 pushes the cam follower 41 of the elongate clip 40 radially inward, which causes the barrel 16 to wind in as more and more of it submerges under its outer end 54 to decrease its diameter. This in turn causes the heaters 21 to be squeezed radially inward as well.

The barrel-adjustment assembly 18 and the barrel 16 can be constructed to provide a plurality of preset barrel diameters that are commonly used and seen in the market. For example, the rotary collar 32 and the handle 12 can cooperatively define detents that form discrete, repeatable rotational positions to produce a minimum and maximum diameter of the barrel 16 of 0.75 and 1.75 inches, respectively, with 0.25 inch increments. In this example, the curling iron 10 can be adjusted to five positions having barrel diameters of 0.75, 1.00, 1.25, 1.50, and 1.75 inches, thereby enabling a single one of the curling irons 10 to do the job of five conventional curling irons. One skilled in the art will recognize that a number of possible combinations and permutations for the sizing and arrangement of the barrel 16 and the barrel-adjustment assembly 18 can be provided to produce a number of different barrel sizes and discrete adjustment positions.

The adjustable distal end assembly 22 is located at and forms the distal end of the curling iron 10. The adjustable distal end assembly 22 can include a distal tip cover 70 and a plurality of fan blades 72 (see FIG. 17). The fan blades 72 are coupled to and extend between the tip cover 70 and the distal end of the barrel 16 such that they overlap and layer upon one another in a decreased-diameter arrangement when the barrel 16 is in the contracted position and they fan out into an increased-diameter arrangement when the barrel is in the expanded position. In this way, the adjustable distal end assembly 70 provides adjustable coverage for the open end of the barrel 16 as its diameter is radially adjusted (increased or decreased). Further details of one such adjustable distal end assembly 22 of a typical commercial embodiment are disclosed related U.S. patent application Ser. No. 12/880,427, filed Sep. 13, 2010.

With reference now to FIGS. 18-19, there are shown major components of an adjustable-barrel curling iron 110 according to a second example embodiment. The curling iron 110 is similar to that of the first embodiment in that it includes a handle 112, a pivotal clip 114, a radially adjustable barrel 116, a barrel-adjustment assembly 118, a radially-adjustable heater assembly 120, and a distal tip assembly (not shown). The barrel-adjustment assembly 118 includes the rotary collar ring 134 defining the spiral cam guide 136. In this embodiment, however, the rotary post 138 has a square cross section and there are four leaf springs 148 and four heaters 121.

With reference now to FIGS. 20-21, there are shown major components of an adjustable-barrel curling iron 210 according to a third example embodiment. The curling iron 210 is similar to that of the second embodiment in that it includes a handle 212, a pivotal clip 214, a radially adjustable barrel 216, a barrel-adjustment assembly 218, a radially-adjustable heater assembly 220, and a distal tip assembly 222. In this embodiment, the distal tip assembly 222 includes at least two extension blades 272 that extend distally from the distal end of the barrel and rotate independently of each other about the pivotal end 274 of the rotary post 238 to help the barrel 216 adjust radially inward and outward uniformly along its length.

With reference now to FIGS. 22-31, there are shown major components of an adjustable-barrel curling iron 310 according to a fourth example embodiment. The curling iron 310 is similar to that of the above-described embodiments in that it includes a handle 312, a pivotal clip (not shown), a radially adjustable barrel 316, a barrel-adjustment assembly 318, a radially-adjustable heater assembly 320, and a distal tip assembly 322. The radially-adjustable heater assembly 320 includes at least one heater 321 and a central rotary post 338.

Referring to FIGS. 22-25, in this embodiment the heaters 321 that are not coupled to the heater guide bracket 380 each include a guide plate 382 to prevent interference and restriction by the heater guide bracket. In a typical commercial embodiment, the guide plates 382 can be provided by copper plates, for example, 0.15 mm TK plates mounted to the heater jacket housings 355 by eyelets (see FIG. 22). The heater guide bracket 380 is coupled to the barrel 316 inside the barrel adjacent its inner edge 352 (see FIG. 23). One of the heaters 321 (e.g., its jacket housing 355) couples to the heater guide bracket 380 (e.g., by sliding into inward lips formed by end channel portions of the bracket). So when the central rotary post 338 and its heaters 321 are rotated, the inner edge 352 of the barrel 316 is rotated with them to wind the barrel about the post and adjust the diameter (see FIGS. 24-25), as can be seen by reference to the relative positions of the inner and outer edges 352 and 354 of the barrel.

Referring to FIGS. 26-28, the distal end assembly 322 of this embodiment is not adjustable. However, it includes a distal tip cover 370 defining a spiral cam guide 384 that cooperates with a cam follower 386 that is attached to the distal end of the barrel 316. In the depicted embodiment, the spiral cam guide 370 is formed by a spiral groove, for example, about 3 mm deep. The spiral cam guide 384 conforms to the configuration of the spiral cam guide 36 of the rotary collar 33 (except that it is reversed), and the cam follower 386 can be formed by the distal end of the elongate clip 40 that also forms the cam follower 41. In this way, rotation of the rotary collar causes both ends 352 and 354 of the barrel 316 to be rotated synchronously. This helps with the alignment of the barrel 316 as it is adjusted radially and controls the gap between the barrel and the outer edge 354. In addition, the distal tip cover 370 can be mounted in place for example by an insert pin screw 388, a self-locking nut 389, and a screw cover 390.

Referring to FIGS. 29-31, the proximal end of the central post 338 can include a stopper 344 and the handle 312 can include at least one cradle portion 346 that receives the post and abuts the stopper to constrain the post from linear movement, while still permitting its free-floating rotational movement. The central post 338 can also include one or more bearings 391 to facilitate a smooth rotational operation. Also, the non-circular portion of the post 338, which is triangular in the depicted embodiment, can be formed by mounting (e.g., spot-welding) panels 392 onto the post.

It should be noted that the features of each of the embodiments described herein can be combined in other embodiments not expressly described herein. Thus, one or more features of one of the embodiments can be combined with one or more features of another one of the embodiments to form yet another embodiment.

While the invention has been shown and described in example forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention as defined by the following claims. 

1. An adjustable-barrel curling iron, comprising: a handle; a pivotal clip mounted to the handle; a radially-adjustable barrel extending longitudinally from the handle, having an outer end and an inner end that overlap each other in a spiral configuration, and radially adjustable between expanded and contracted positions having different diameters; a heater assembly that provides heat to the barrel; and a barrel-adjustment assembly including a rotary ring that defines a spiral cam guide and a cam follower extending from the barrel and driven by the spiral cam guide, wherein the rotating the ring relative to the handle rotates the spiral cam guide, which displaces the cam follower radially inward or outward, which in turn displaces the outer end of the barrel radially inward or outward to adjust the barrel between the expanded and contracted positions.
 2. The adjustable-barrel curling iron of claim 1, wherein the spiral shape of the cam guide is selected so that the barrel is concentric at every position as the cam follower is guided radially inward and outward by the spiral cam guide.
 3. The adjustable-barrel curling iron of claim 1, wherein the spiral cam guide is formed by a spiral groove in the rotary ring and the cam follower is formed by an elongate clip attached to the barrel.
 4. The adjustable-barrel curling iron of claim 3, wherein the cam follower has an enlarged head and the spiral cam guide groove has an enlarged portion through which the enlarged head fits, and wherein the enlarged head does not fit through the rest of the spiral cam guide groove.
 5. The adjustable-barrel curling iron of claim 1, wherein the rotary ring includes a collar for user grasping and rotation.
 6. The adjustable-barrel curling iron of claim 1, wherein the heater assembly is radially adjustable and includes a central rotary post, at least one heater, and at least one spring mounted between the heater and the post.
 7. The adjustable-barrel curling iron of claim 6, wherein the spring biases the heater radially outward so that, as the diameter of the barrel is adjusted, the heater remains in contact with the barrel.
 8. The adjustable-barrel curling iron of claim 6, wherein the spring includes a clip that couples the heater to the spring.
 9. The adjustable-barrel curling iron of claim 6, wherein the at least one heater comprises three heaters and the central post has three sides and a triangular cross section, with each one of the heaters mounted to a corresponding one of the sides.
 10. The adjustable-barrel curling iron of claim 6, wherein the central post is coupled to and rotationally driven by the rotary ring.
 11. The adjustable-barrel curling iron of claim 10, wherein rotary ring has an opening through which the central post extends, and wherein the ring opening and the central post have confirming geometry so that rotating the rotary ring causes the post to rotate with it.
 12. The adjustable-barrel curling iron of claim 6, wherein the handle includes a fixed ring that is adjacent the rotary ring and has an opening through which the central post extends freely without constraint, the post includes a stopper, and the handle defines a cradle that receives the post and abuts the stopper to constrain the post from linear movement while still permitting its free-floating rotational movement.
 13. An adjustable-barrel curling iron, comprising: a handle; a pivotal clip mounted to the handle; a radially-adjustable barrel extending longitudinally from the handle, having an outer end and an inner end that overlap each other in a spiral configuration, and radially adjustable between expanded and contracted positions having different diameters; a radially adjustable heater assembly that provides heat to the barrel and that includes a central rotary post, at least one heater, and at least one spring mounted between the heater and the post, wherein the central post is rotationally driven by the rotary ring, and wherein the spring biases the heater radially outward; and a barrel-adjustment assembly including a rotary ring that defines a spiral cam guide and a cam follower extending from a proximal end of the barrel and driven by the spiral cam guide, wherein the spiral cam guide is formed by a spiral groove in the rotary ring and the cam follower is formed by an elongate clip attached to the barrel, wherein the rotating the ring relative to the handle rotates the spiral cam guide, which displaces the cam follower radially inward or outward, which in turn displaces the outer end of the barrel radially inward or outward to adjust the barrel between the expanded and contracted positions, wherein the spiral shape of the cam guide is selected so that the barrel is concentric at every position as the cam follower is guided radially inward and outward by the spiral cam guide, wherein as the diameter of the barrel is adjusted, the heater remains in contact with the barrel due to the spring biasing the heater radially outward.
 14. The adjustable-barrel curling iron of claim 13, wherein the cam follower has an enlarged head and the spiral cam guide groove has an enlarged portion through which the enlarged head fits, and wherein the enlarged head does not fit through the rest of the spiral cam guide groove.
 15. The adjustable-barrel curling iron of claim 13, wherein the rotary ring includes a collar for user grasping and rotation.
 16. The adjustable-barrel curling iron of claim 13, wherein the spring includes a clip that couples the heater to the spring.
 17. The adjustable-barrel curling iron of claim 13, wherein the at least one heater comprises three heaters and the central post has three sides and a triangular cross section, with each one of the heaters mounted to a corresponding one of the sides.
 18. The adjustable-barrel curling iron of claim 13, wherein rotary ring has an opening through which the central post extends, and wherein the ring opening and the central post have confirming geometry so that rotating the rotary ring causes the post to rotate with it.
 19. The adjustable-barrel curling iron of claim 13, wherein the handle includes a fixed ring that is adjacent the rotary ring and has an opening through which the central post extends freely without constraint, the post includes a stopper, and the handle defines a cradle that receives the post and abuts the stopper to constrain the post from linear movement while still permitting its free-floating rotational movement.
 20. The adjustable-barrel curling iron of claim 13, further comprising a cam follower extending from a distal end of the barrel and a distal-tip assembly defining a spiral cam guide that cooperates with the cam follower and that conforms to the configuration of the spiral cam guide of the rotary ring, except that it is reversed, so that rotation of the rotary collar causes the proximal and distal ends of the barrel to be rotated synchronously. 